About unlimited domains in Hostgator(web hosting))

Hi, i am a bit confused about the meaning of unlimited domain offered in Hostgator baby plan/ plan in blue host.
Does that mean the package itself would include free domain names that I need not to purchase domain names anymore? Or it means that it allow you to point to domain names you have already bought only?
I am a newbie interested in frontend development. Recently, I am hoping to build my personal protfolio and some demos of websites online such that I can get a job as a frontend developer.
Any advices are welcome… thank you!!

You still need to register (ie pay for) each name. It just lets you have “unlimited” numbers of them on your hosting. Note that this isn’t really much of a feature – very often you don’t normally want unlimited domains, you just want one

You can have unlimited sub-domains or add-on domains I guess.
eg) www.maindomain.com

Add on domains can be domain names bought elsewhere and hosted under one of your subdomains.